This invention relates to an aqueous coating composition and in particular to an aqueous thermosetting coating composition that can be electrodeposited or applied by conventional techniques.
It is well known to electrodeposit carboxylic polymers as shown in Gilchrist U.S. Pat. No. 3,230,162, issued Jan. 18, 1966; Gilchrist U.S. Pat. No. 3,362,899, issued Jan. 9, 1968; Sekmakas et al. U.S. Pat. No. 3,516,913, issued June 23, 1970 and Sekmakas et al. U.S. Pat. No. 3,536,641, issued Oct. 27, 1970. Coating compositions of epoxy ester resins have been applied by electrodeposition as have coating compositions of resins of maleinized drying oils but these compositions either had inadequate throwing power or poor stability in the electrocoating bath or finishes from these compositions had unacceptable corrosion and saponification resistance. Compositions in which these resins were blended had similar failings and often exhibited preferential deposition of one of the resins in the electrocoating process.
The novel composition of this invention utilizes the reaction product of an epoxy ester resin and a maleinized drying oil to form a coating composition for electrodeposition which has excellent throwing power, good bath stability, good corrosion and a saponification resistance. The novel composition also can be applied by conventional techniques and can be used as a primer surfacer composition.